.\" $NetBSD: wcwidth.3,v 1.4 2017/07/03 21:32:49 wiz Exp $
.\" FreeBSD: src/lib/libc/locale/wcwidth.3,v 1.6 2004/08/17 04:56:03 trhodes Exp
.\"
.\" Copyright (c) 2002 Tim J. Robbins
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.Dd August 17, 2004
.Dt WCWIDTH 3
.Os
.Sh NAME
.Nm wcwidth
.Nd "number of column positions of a wide-character code"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft int
.Fn wcwidth "wchar_t wc"
.Sh DESCRIPTION
The
.Fn wcwidth
function determines the number of column positions required to
display the wide character
.Fa wc .
.Sh RETURN VALUES
The
.Fn wcwidth
function returns 0 if the
.Fa wc
argument is a nul wide character (L'\e0'),
\-1 if
.Fa wc
is not printable,
otherwise it returns the number of column positions the
character occupies.
.Sh EXAMPLES
This code fragment reads text from standard input and
breaks lines that are more than 20 column positions wide,
similar to the
.Xr fold 1
utility:
.Bd -literal -offset indent
wint_t ch;
int column, w;

column = 0;
while ((ch = getwchar()) != WEOF) {
	w = wcwidth(ch);
	if (w > 0 && column + w >= 20) {
		putwchar(L'\en');
		column = 0;
	}
	putwchar(ch);
	if (ch == L'\en')
		column = 0;
	else if (w > 0)
		column += w;
}
.Ed
.Sh SEE ALSO
.Xr iswprint 3 ,
.Xr wcswidth 3
.Sh STANDARDS
The
.Fn wcwidth
function conforms to
.St -p1003.1-2001 .